1

V.A. Khoze (IPPP, Durham)

(In collaboration with L. Harland-Lang, M. Ryskin and W.J. Stirling)

Outlook on Central Diffractive Processes at the Tevaron , LHC and RHIC

CDP

07 May 2010, CERNDIFFRACTION@LH

C

7 May 2010

Forward proton distributions and correlations.

Tevatron, LHC and RHIC.

(star reactions!)

D0, RHIC datato come soon

Detailed tests of dynamics of soft diffraction (KMR-02)

Spin-Parity Analyzer

“soft” scattering can easily destroy the gaps

gap

gap

eikonal rescatt: between protonsenhanced rescatt: involving intermediate partons

M

soft-hardfactorizn

conservedbroken

Subject of hot discussions nowadays :Subject of hot discussions nowadays : S²S²enhenh

S² absorption effects -necessitated by unitarity

Everybody’s ~ happy (KMR, GLMM, FHSW, KP,Petrov et al, BH, GGPS, Luna...MCs)

‘Better to light a candle than to rant against darkness’

( Confucius )

Standard Candle ProcessesStandard Candle Processes

CDF & DO (Christina, Mike)

7

(Currently no complete theoretical description of onium properties.)

(BABAR (2008) (Still puzzles)

(spins- still unconfirmed)

The heaviest and most compact quark-antiquark bound state in nature

Our 3 measurements are all in good agreement (factor “few”) with the Durham group predictions.

*

*

*Prpospects !

FSC@LHC (Mike)

(more coming soon )

(Christina, Mike)

(Gap Detectors in no P-U events)

What we expect within the framework of the Durham formalism (KMR-01, KKMR-03, KMRS-04, HKRS-10)

Example, O++ -case

*KNLO

Strong sensitivity to the polarization structure of the vertex in the bare amplitude.

Absorption is sizeably distorted by the polarization structure (affects the b-space distr.)

KMR-02, KKMR-03

KMR-01

Forward proton distributions & correlations- possibility to test diffraction dynamics

KMR-02

(Gap size

Too good to be true ?!

Phys.Rev.Lett.102:242001,2009

(HKRS-09)

Diphoton CEP

(A. Alekseev-1958-positronium)

(R.Pasechnik et al, Phys.Lett.B680:62-71,2009; HKRS, Eur.Phys.J.C65:433-448,2010)

KMR-01

1 : 0.6 : 0.22

2

and accounted for in the integrand

CDF

Spin-parity Analyzer

Central Diffractive Production of

(Crystal Ball -1986)

(about 0.25 of all hadronic decays (CLEO-2009)

(Barbieri et al (1979), NRQCD )FSC@LHCb ?

Suppressed non-resonant background

3 % .

1 : 0.03 : 0.08

(0 ) /d d

Very topical for STAR@RHIC forthcoming measurements with tagged forward protons(HKRS results soon to come).

KKMR-03

0+ 1+

2+ 0-

0+ 1+

2+0-

(HKRS-2010)

HKRS-results at different energies, and cuts are now available.

New(Leading term QCD expectations)

Central production with RPs @STAR is taking of. First pppXp data.Partial wave analysis- soon.

Rich diffractive structure of the cross sections as a function of proton momenta

Ongoing HKRS studies for RHIC energies and kinematics.Correlations between transverse momenta of outgoing protons

KMR-02

Interesting to compare the results for different states.

LHCbExcellent particle ID (pion/Kaonseparation), vertex and proper

time resolutionexotic states….

Potentially rich program of CDP studies with the LHCb

JINST 4:P11019,2009.

Disclaimer : up to the experts to deliver a verdict

JINST 4:P11019,2009.

(CDP background to the luminometer )

, KK, ,

, dijet, diphton CEP- rich program of studies at the LHC; promising potential of LHCb.

New STAR@RHIC results on CEP with tagged forward protons soon to come.

Currently active studies are in progress (both in theory and experiment).

Prospects of CDP studies at ALICE (Rainer)

Thank You

29

UNCERTAINTIES UNCERTAINTIES

Known Unknowns

Unknown Unknowns

N(N)LO- radiative effects (K-factors etc..) ‘…possible inadequancy of PT theory in s …’ R.Barbieri et al-1980 ‘ ‘Right’ choice of gluon densities, in particular at so low scales as in the case ( potentiality of a factor of ~3 rise for the H-case ) .

Complete model for calculation of enhanced absorption. -experimental widths, decays…

Gluons at so low scales, surprises are not excluded at all.

c

b

Non- pQCD effects in the meson characteristics. Currently no complete description of heavy quarkonium characteristics.‘Two gluon width does not tell the whole story.’

Factor of 5 up or down Factor of 5 up or down (at best) (at best)

)

and

MRST99 and MSTW08LO PDFs provide approximately upper and lower bounds respectively

Ratios of cross sections at different energies- uncertainties

DIPHOTON CEP

Are the early LHC runs,without proton taggers,able to check estimatesfor pp p+A+p ?

Possible checks of:

(i) survival factor S2: W+gaps, Z+gaps

(ii) generalised gluon fg : p p

(iii) Sudakov factor T : 3 central jets

(iv) soft-hard factorisation #(A+gap) evts (enhanced absorptive corrn) #(inclusive A) evts with A = W, dijet, …

gap

gapKMR: 0802.0177

Divid

e et

Impe

ra